在酿酒酵母中重构正交萜类合成途径

酿酒酵母是生物安全级的工业微生物，具有强大的甲羟戊酸途径，是合成植物源萜类的理想底盘细胞。但异源萜类合成途径与酵母天然鲨烯代谢途径共享反式前体或底物，相互串扰，活性产物合成低效。如何平衡酿酒酵母内源鲨烯代谢与异源萜类合成是当前微生物代谢与合成生物学的前沿和关键学科问题。本项目另辟蹊径，以顺式前体和底物，与酵母内源反式前体和底物形成正交关系，在酿酒酵母细胞质和细胞器中重构倍半萜或二萜合成代谢途径，研究异源萜类产物合成与酿酒酵母底盘细胞基础代谢的相互关系。理论上，优化异源正交途径与底盘细胞代谢的平衡，阐明正交合成代谢途径的适配性和调控机制，为异源萜类高效合成积累新知识和新原理。应用上，建立萜类异源正交途径的调控技术，获得工程酵母菌株，拓展萜类产物异源合成代谢的调控前沿。

Saccharomyces cerevisiae, an industrial microbe generally recognized as safe (GRAS), is considered as a promising cell factory for production of plant terpenoids because of the potent mevalonate (MVA) pathway. However, the heterologous biosynthetic pathway of terpenoids share the trans-precursors or trans-substrates with the native squalene pathway of yeast. They cross talk with each other and thus impair the biosynthesis of products of interest. Balancing the native squalene pathway and heterologous terpenoid pathway is the frontier of metabolic engineering and synthetic biology. The project alternatively employs the cis-precursors and cis-substrates, which is orthogonal with the native trans-precursors and trans-substrates. The synthetic pathway of the heterologous sesquiterpenoid or diterpenoid would be constructed and functioned in the cytoplasm and the organelles of Saccharomyces cerevisiae. The interactive relationships between the heterologous biosynthesis of terpenoids and the native metabolism of the chassis would be investigated. Theoretically, the project would conclude the new knowledge by optimizing the heterologous orthogonal pathway and native metabolism and elucidating the fitness and regulation mechanism of the orthogonal synthetic pathway. Practically, breaking through the bottleneck of the pathway regulation would provide technical supports for efficient production of terpenoids with complex structures harboring the long biosynthetic pathways via establishing the regulation strategy of the orthogonal terpenoids pathway and engineering the recombinant yeast strains.